1. Field of the Invention
The present invention relates to an indwelling needle for an infusion set, which has a down-sized constitution and is capable of regulating the amount of a blood back-flow.
2. Description of the Related Art
Indwelling needles are used to infuse various medicinal fluids into vascular systems. In some case, an indwelling needle is provided with an inner needle for being stuck into a vascular system and an outer needle coaxially fit on the inner needle. After sticking, the inner needle may be extracted but the outer needle is left inserted and used for infusion.
Japanese Patent Application Laid-open JP2002-102347 discloses an art of an indwelling needle assembly provided with a needle cover and blood monitoring means. The needle cover is configured to cover the inner needle and the blood monitoring means and hence assures safe disposal thereof without accidental sticking after use. The blood monitoring means is movably housed in the needle cover and provided with a chamber for receiving back-flow of blood. When the inner needle is inserted in the vascular system, an operator can observe the back-flow of the blood pooled in the chamber from the exterior so as to verify the inner needle is regularly inserted in the vascular system.